goboykin

I replaced my battery in my 85 GSLSE. When I did this I received some significant arcing. The fusible link was blown. I checked the voltage at the terminals and found a curious thing. When I attached the leads of the voltmeter to the negative terminal and to the frame, I get 12.5 volts. When I attach the leads to the positive terminal and to the frame, I get zero volts. What is going on with this? Are the 1st generation RX-7s positively grounded??? Help. I don't want to blow another fusible link.

85rotarypower

Sounds like you hooked up your battery backwards. Check the markings on the battery for negative and positive. Negative should be to the front of the car.

goboykin

I checked and it is connected like you said.

85rotarypower

Thats strange. I don't know whats wrong then.

Dom

There are two possibilities:

- The battery is hooked up backwards

- The leads on your meter are backwards

To repair the fusible link, strip off the insulation, and twist the two ends together.

goboykin

The battery is connected properly and the leads were as well.

64mgb

iTrader: (1)

Well, if you get 12 volts from negative to ground, and zero from positive to ground, it's definitely hooked up backwards, which is a bad situation. On mine ('79) the negative is toward the back of the car. Take some pictures...maybe we can spot something.

goboykin

Is it possible that I have a short on the positive side???

partsguy74

If you have a short to ground, you could see 12 volts on the body ground, but that assumes you have voltage on the positive side of the battery too (closed loop circuit). So, unless you have to power sources in your car, something is in backwards.

64mgb

iTrader: (1)

If you had a short to ground, you wouldn't see any voltage anywhere. You connect two things together (which is what a short is) and there is no chance for a voltage drop across them.

partsguy74

Oops.. my bad.. you're correct 64mgb..

goboykin

I have the cable with the yellow stripe connected to the positive terminal on the battery. I believe it comes from the starter. Is this the correct configuration??

partsguy74

The cable from the starter goes to the positive and the cable from the engine block goes to ground.. You might want to pull the battery and have it checked at advance or autozone. there may be something weird going on with that battery. I have heard, never seen, a battery come out of the manufacturing plant with a reverse charge.. more like they put the positive and negative indicators on the wrong way.. Sounds strange, but I'm out of ideas for ya.

goboykin

Thanks for the help!

Feds

I think stripe cable is negative. Here is the definitive way to tell:

The positive batery cable has a smaller gauge wire that y's off of the main cable and connects to the block that contains the fusable links. THAT is the positive batery cable.

I once hooked my batery up backwards, and it arced, and burned a fusible link

64mgb

iTrader: (1)

Disconnect the battery completely and measure the voltage across the terminals. Pay close attention to the way the probes are connected to the voltmeter. Make sure the red probe is connected to the plus terminal on the voltmeter and the plus terminal on the battery. Make sure the black probe is connected to the minus terminal on the voltmeter and the minus terminal on the battery. You should see a positive voltage on the voltmeter. If you read a negative voltage, the battery is marked wrong. I've never seen this happen and would be very surprised if it happens, but you never know.

While the battery is disconnected carefully trace the two battery cables to see where they are connected at the other end. One should go directly to the chassis or engine...this is the ground (negative) cable. You should be able to measure resistance from the battery end to ground and see zero resistance. The other cable probably goes to one of the terminals on the starter...this will be your positive cable.

Hope this helps.

Rich

goboykin

I checked the battery as you suggetsed w/ the (+) end of the voltmeter and the (+) terminal of the battery and the (-) end of the voltmeter with the (-) terminal of the battery. I got a + 12.5 volts. This indicates to me that the battery is correctly labelled.

I thought the yellow cable led to the starter which I had connected to the (+) terminal of the battery. I will recheck to make sure.

Can you think of anything else I can check?

Thanks....

64mgb

iTrader: (1)

Check out the 4th picture on this page:
http://85rx7.home.mchsi.com/85rx7_20041204.html

It shows where the ground cable connected to a transmission bolt. It's black with a yellow stripe.

Rich

grease

the battery cable with the yellow stripe should be the groung cable. positive cable is solid black.

RotorMotorDriver

iTrader: (1)

Yup yup, as stated, just look at the cable ends that hook to the terminals. The ground wire has only one cable. The positive has the cable as well as a smaller wire that goes to the fuseable link box. If you hooked it up backwards, which it sounds like you did, then you would fry a fuseable link. Ive done it.

~T.J.

Bob Holton

Dont feel bad, I think we have all done that at least once. Bob